The present invention relates to flapper-type flush valve for toilets, particularly for tank-style, gravity flow toilets and, more particularly, to the effective operation of such flush valves.
A typical tank-style, gravity flow toilet comprises a tank and a bowl. The tank stores a quantity of water for flushing the toilet. A flush valve is disposed in the tank. A typical flush valve is a xe2x80x9cflapper-typexe2x80x9d flush valve, including a rigid backing plate and a flexible valve disposed beneath the backing plate. The valve seal sits atop a discharge pipe in the tank and, when the flush valve is operated, allows the quantity of water stored in the tank to be delivered by gravity flow to the toilet bowl for flushing the toilet.
U.S. Pat. No. 4,841,579, incorporated in its entirety by reference herein, discloses a flapper-type flush valve for toilets. Attention is directed to FIGS. 6-8 therein which illustrate a flush valve comprising a flat, circular, rigid backing plate (50) with a central post portion (53) extending centrally from a bottom surface thereof and a float portion (51) on the top surface thereof. A conical guide portion (52) extends from the post portion (53). The central post portion (53) has a peripheral groove (54) to receive an inner circular edge (54a) of a flat, resilient, disc-like valve seal (55). The valve seal (55) is parallel to and spaced slightly apart from the bottom surface of the backing plate (50). When the valve is closed, the valve seal is forced against the valve seat which is the top end of the discharge pipe. The slight spacing of the inner edge valve seal from the backing plate enables the valve seal to flex, thereby effecting a good seal on the valve seat. However, this flexing (distortion), and resulting non-planarity of the valve seal also results in a cavity (region) being formed between the valve seal and the backing plate since the outer peripheral portion of the valve seal is forced against the planar bottom surface of the backing plate while the inner edge of the valve seal is maintained in spaced relationship from the bottom surface of the backing plate. As disclosed in this patent, this spacing of the valve seal from the backing plate, and resulting cavity (region) formed therebetween xe2x80x9cappears somehow to lead to leakage of the valvexe2x80x9d (column 4, lines 47-49). It is therefore proposed in this patent to provide one or more vent ports (62) in the backing plate so as to allow air which is trapped in the region (cavity) between the valve seal and the backing plate to escape, thereby permitting equalization of fluid pressures in the tank and in this region. And further, that xe2x80x9cfor reasons that are not fully understood, this prevents the valve from leaking as a consequence of valve seal distortion.xe2x80x9d (column 4, lines 50-57).
An object of the invention is to provide an improved flapper-type flush valve for toilets, particularly for tank-style, gravity flow toilets.
Another object of the invention is to ensure effective operation of flapper-type flush valves, particularly ensuring a good seal between the valve seal and the valve seat, and more particularly preventing the valve from leaking as a consequence of valve seal distortion.
Applicant proposes that the aforementioned leakage problem discussed in U.S. Pat. No. 4,841,579 arises from the fact that air trapped in a cavity which is formed between the valve seal and the backing plate provides sufficient buoyancy to float the flush valve flapper out of intimate sealing engagement with the flush valve seat. Accordingly, an aspect of the invention is to provide structure for preventing the formation of a cavity between a flush valve backing plate and a flush valve seal. By preventing the formation of the cavity, it is therefore not necessary to vent the cavity, as proposed in the aforementioned U.S. Pat. No. 4,841,579.
According to the invention, at least one channel is formed in a backing plate of a flush valve, on a surface facing the flexible valve seal. The at least one channel preferably extends radially to an outer edge of the backing plate, preferably in a xe2x80x9cforwardxe2x80x9d direction which is opposite a direction of arms extending xe2x80x9crearwardlyxe2x80x9d from the backing plate for attachment of the flush valve flapper to a standpipe.
According to a feature of the invention, the channels have a depth, and the valve seal is space a distance from the backing plate. The channel depth is one-half of the distance that the valve seal is spaced from the backing plate.
In an embodiment of the invention, the channels may be formed by pairs of ridges, on the surface of the backing plate, wherein each pair of ridges forms a channel, and one of a plurality of channels extends in the xe2x80x9cforwardxe2x80x9d direction.
In an alternate embodiment of the invention, the channels are a plurality of wedge shaped channels extending into the surface of the backing plate, and one of a plurality of channels extends in the xe2x80x9cforwardxe2x80x9d direction.
Other aspects, features and advantages of the invention will become apparent in light of the following description thereof.
Reference will be made in detail to preferred embodiments of the invention, examples of which may be illustrated in the accompanying drawing figures. The figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these preferred embodiments, it should be understood that it is not intended to limit the spirit and scope of the invention to these particular embodiments.
Selected parts of the drawings hereinafter described may be shown out of scale for the sake of illustrative clarity. Moreover, cross-sectional views, if any, that are included herein may be focused on and limited to a view along the line of the cross-section and omit background structure that would otherwise be shown in a true cross-sectional view, again, for the sake of illustrative clarity.
Generally, in the following drawings, like reference numerals, that are either unprimed, primed or double primed, may designate like or corresponding parts throughout the several Figures.